The invention relates to an integrated circuit arrangement including a differential amplifier whose outputs are coupled to a load resistor arrangement and to a transistor arranged as an impedance transformer, and whose control input is coupled to a current source.
Such an integrated circuit arrangement including a differential amplifier with impedance transformers connected to its outputs is particularly used in a circuit for high frequencies, for example in the GHz range. A 2:1 multiplexer whose output circuit includes a differential amplifier with two bipolar transistors is known from the ITG Fachbericht 103, Mikroelektronik fur die Informationstechnik, lectures at the ITG Conference of 3 to May 10, 1988 in Berlin, "Grundschaltungen fur die optische Breitbandkommunikation bis 10 GBit/s mit einem einfachen selbstjustierenden SI-Bipolarproze{-Proze{charakterisierung und Schaltungssimulationen", H. -U. Schreiber and U. Langmann, VDE Verlag, pp. 21 to 26. The emitters of the two transistors of the differential amplifier are connected together and constitute the control input of the differential amplifier which is connected to a current source. Such a current source is generally realised by means of a transistor. The input signal is applied to the base terminals of the two transistors of the differential amplifier. A load resistor arrangement comprising a resistor and two further series-arranged bipolar transistors arranged as emitter followers (impedance transformers) are connected to the collector of each transistor (outputs of the differential amplifier). Based on the current source at the control input of the differential amplifier, the collector currents of the differential amplifier are also substantially constant in the case of a change of temperature. The direct voltage at the collectors is also substantially constant due to the constant collector currents. The base-emitter voltage of an emitter follower is dependent on the temperature. When the temperature changes, the output voltage of the integrated circuit arrangement changes as well. This change is conditioned by a change of the base-emitter voltage of the emitter follower. A base-emitter voltage change of approximately -2 mV/K of an emitter follower results in a voltage change of -200 mV for each emitter follower at the output of the differential amplifier in a range of -20.degree. C. to 80.degree. C. The change of the output voltage at temperature changes may lead to unwanted conditions of operation in subsequent circuit arrangements.